There has been much buzz about Shōchū slipping into your nicer bars and cocktails. Immediately many drinkers here the word and think, “Soju?”

It’s easy to get confused. No, Shōchū is not the cheap(er) Korean booze in the little green bottles. It’s a distilled spirit made from various ingredients, including rice, barley, sweet potatoes, brown sugar, or buckwheat. There are some rarer Shōchū made from other ingredients.

The green bottle Korean soju is diluted from pure grain alcohol with added flavorings. It’s a product for mass consumption, and it certainly satisfies the masses.

BUT HOLD ON THERE.

There is still another Korean soju–let’s call it the traditional kind. Or how about Sool Soju? (Hey, that sounds familiar.)

Before the green bottle soju we all know from K-Town BBQ houses there was a long tradition of Sool dating back millennia. Sool making was a treasured longstanding tradition in Korea before Japanese colonial occupation (1910-1945) actively sought to wipe it out. 

During Korea’s economic rise, green bottle soju became the norm. It’s only recent that the old traditions have been revived. In the meantime, Japan has had a bit of a head start. This is a story for another time.

Let’s talk about the differences between Japanese Shōchū and Korean Sool Soju. They are each glorious and fascinating. Get ready to nerd out, rice whiskey fans.

The Rice

Japanese Shōchū – Clarity is King

Let’s start with the rice. Japanese liquor making uses multiple types of rice. It gets polished and polished to get to the inner clear starches. The more it’s polished, the more prized and expensive it is because one has to go through a lot of rice to get a small amount of the super polished stuff.

The clearer the rice the cleaner the fermentation. The Platonic ideal is to end up with an elixir of the utmost clarity. 

Korean Sool – Cloudy is Good

Clarity is not the goal for Korean Sool. It can be a result, but other factors come into play, like taste and body. Korean Sool connoisseurs have no problem with cloudy, at times milky, rice sediment. Some even prize it. That’s not a flaw. It’s a feature.

Fermentation Styles

Shochu

Credit: 8 Kome on Flickr (cc)

Japanese Shōchū – All Warm and Koji

It all comes down to the type of mold. In Shōchū’s case, it’s Koji. This mold is an isolated strain controlled in Japan’s government labs. They replicate it to a consistent quality. This makes it ideal for mad scientist brewers who want to create something precise. There are versions of Koji they can order from the labs to suit their wildest whims.

To prepare, the polished rice is steamed. Then it’s peppered with the Koji in something akin to a pepper shaker. It’s heated for 48 to 72 hours. This is the inoculation stage. The Koji mold attaches itself to each rice grain and buries through its structure. Each grain is covered with white mold. This is called Koji Rice and is the fermentation starter.

Koji Rice

Koji Rice. Credit: Mattie Hagedorn (cc)

Brewers add more rice, water, and yeast. You could make your sourdough comparisons here. It’s extremely controlled and consistent. The process itself is respected throughout Japan.

Korean Sool – Funky Wild Nuruk

A notable difference between the Japanese aesthetic and the Korean one is that of control vs. laissez-faire. Japanese artforms aim to control nature to an imagined ideal–Bonsai trees, Zen gardens. The Korean aesthetic prefers to guide nature but let it do its own thing. A traditional Korean table or bench follows the contours of the tree, never following a straight line. A proper Korean garden is “plant it and forget it.” 

This also goes with spiritcraft. 

Nuruk

Nuruk. Credit: Wikimedia Commons (cc)

Where Japan has Koji, Korea has Nuruk. It’s not grown in labs. Quite the opposite. It’s a wild fermentation starter. 

You get a host–wheat, wheat flour, mung beans–and add just enough water for cohesion. This is the tricky part. It has to be just enough. 

Then it’s packed into a circular or square frame. The spirits master puts it on the floor, covers it with a cloth, and stamps on it with her feet. Traditionally Korean alcohol was made by women. 

Next the Nuruk is left for fermentation. The first seven days are an incubation state. The Nuruk is placed with hay or pine needles and left in a room with a balmy temperature between 26 and 32 degrees Celsius (79-89.6 degrees Fahrenheit). The swampy sauna encourages mold growth. This is all about attracting mold spores. 

This continues for another seven days in order to get the mold to penetrate the center of the cake.

The last stage is the dry out stage. This is the hardest part–getting the humidity just right. If it’s too dry, the mold will not inoculate on the inside.

When everything goes right, you get a nice block of inoculated Nuruk. Lots of wild stuff has clung to this. Each batch is different, which likely would drive a Japanese liquor maker batty.

This is why Nuruk is important.

The mold converts the rice starch into sugar, just like Koji. Once the sugar blooms, the yeast feasts on it, resulting in ethanol and carbon-dioxide. Makers cool the rice so it’s soft enough for the yeast to get into the sugar. 

This is beautiful symbiotic process. It’s multi-parallel fermentation. You don’t have to do anything else. 

Ain’t nature cool?

This results in a wilder profile. The Sool has a punchier flavor with hints of green apple, pineapple, or banana. This is so in its rougher unfiltered makgeolli and takju forms and in its refined distilled soju form. 

Respect the Rice, Respect the Mold

In the end, the differences between Japanese Shōchū and Korean Sool Soju boil down to the clarity of the rice and the molds. The Japanese styles focus on clear polished rice and lab controlled Koji mold. The Korean styles are less focused on rice clarity and concentrate on making the funkiest wild Nuruk mold.

Either way, each is fun to drink and explore. Now that you have an idea of what to taste, give each a try and tell us what you think.